Leukemia-specific or associated antigens will be detected by heteroantisera raised in rabbits to various leukemia cells and cultured leukemic cell lines. In order to reduce reactivity to normal tissue antigens the immunizing cell will be coated with anti-lymphocytic antiserum made in rabbits. Where necessary the antisera will be absorbed by normal lymphocytes, CLL cells or certain cultured lines in order to further increase its specificity. To determine its specificity the antisera will be tested by complement-dependent cytotoxicity and immunofluorescent tests against a panel of various leukemia cells, cell lines and normal peripheral blood cells. The molecular weight and subunit structure of the leukemia antigens will be determined by the immunoprecipitation and SDS polyacrylamide gel electrophoresis technique. The presence of leukemia-associated antigens will be correlated to 1) the morphological subclass of leukemia 2) the presence of T and B lymphocyte membrane markers 3) the clinical features of the particular leukemia. The presence of new leukemia-associated antigens may provide a new diagnostic marker which will assist in determining the type of therapy needed. The majority of leukemia cells appear to express B lymphocyte alloantigens. Leukemia cells will be typed for these newly discovered B alloantigens in order to in investigate genetic associations which may indicate hereditary resistance or susceptibility to the disease.